Jerome Corsi has been subpoenaed by the special counsel.CreditCreditCharles Sykes/Associated Press

Jerome Corsi, a conspiracy theorist and political commentator with connections to the former Trump adviser Roger J. Stone Jr., has been subpoenaed to testify on Friday before the grand jury in the special counsel investigation into Russia’s election interference and whether Trump associates conspired with the effort, his lawyer said on Wednesday.

The lawyer, David Gray, said that he anticipates that investigators for the special counsel, Robert S. Mueller III, plan to ask Mr. Corsi about his discussions with Mr. Stone, who appeared to publicly predict in 2016 that WikiLeaks planned to publish material damaging to Hillary Clinton’s presidential campaign.

“He fully intends to comply with the subpoena,” Mr. Gray said, adding that the subpoena was not specific about the topic but that he and his client anticipated “it has to do with his communications with Roger Stone.”

Mr. Mueller’s team appears to be zeroing in on Mr. Stone as a possible nexus between the Trump campaign and WikiLeaks, which was used by Russian intelligence officers to spread information stolen from Democrats, according to an indictment by Mr. Mueller’s team. Another former associate of Mr. Stone, the New York political gadfly Randy Credico, is also expected to testify before the grand jury on Friday.

Mr. Stone has maintained that he had no contact with Julian Assange, the founder of WikiLeaks, and that he learned what WikiLeaks was doing through public sources and from Mr. Credico, who had a friend in common with Mr. Assange.

Mr. Corsi, who has worked with the conspiracy theorist Alex Jones on his Infowars operation, has dealt with Mr. Stone on and off for years. Mr. Corsi was also one of the people whom President Trump, before he was a candidate, contacted for information about former President Barack Obama’s birth certificate in pressing the false claim that Mr. Obama was not born in the United States.

Mr. Corsi’s name came up when federal agents stopped and detained a professor and author, Ted Malloch, at a Boston airport last March. Mr. Malloch told NBC at the time that, among other questions, federal investigators asked him about Mr. Stone, whom he had met a handful of times, about WikiLeaks and about Mr. Corsi, who had helped edit one of his books.

In testimony before the House Intelligence Committee last year, Mr. Stone, who had predicted in a 2016 tweet that Mrs. Clinton’s campaign chairman, John Podesta, would face his “time in the barrel,” said he based his tweet off research given to him by Mr. Corsi, whom he identified as an investigative journalist. He said that Mr. Corsi’s research was drawn from public information related to Mr. Podesta’s brother, the lobbyist Tony Podesta.

John Podesta’s private email account was hacked in 2016 and some of the content was posted by WikiLeaks in October 2016, just as Mr. Trump was facing questions about the “Access Hollywood” tape on which he was recorded in 2005 boasting about grabbing women by their genitals.

Correction:

An earlier version of this article misstated Jerome Corsi’s relationship with Infowars. Mr. Corsi had previously worked with Infowars but no longer does.